The importance of the acquired immunodeficiency syndrome (AIDS) needs no discussion. The present proposal will create a comprehensive national cooperative drug discovery group based upon novel thematic approaches to understand and control this disease. Five sets of investigators will collectively exploit their unique skills in immunology, chemistry, cell biology and molecular biology in a dynamic and interdigitating fashion. Employing recombinant technology in a baculoviral system, the Reinherz group has produced a secreted form of the CD4 extracellular segment which avidly binds the HIV gp120 without affecting normal immune responses directed against MHC class II. Synthetic CD4 peptides, truncated CD4 proteins and CD4 proteins altered by site-directed mutagenesis as wellas side chain modifications will lead to elucidation of the gp120 binding region. Crystallographic resolution of CD4 will be undertaken collaboratively with Drs. Wiley and Harrison. At the same time, will exploit their skills in immunotoxin (IT) chemistry and the unique CD4-gp120 interaction in order to develop CD4-toxins for targeting the death of HIV-infected cells. Several immunochemical as well as recombinant approaches with various CD4 analogs will lead to discovery of immunotoxins with optimal pharmacokinetics for in vivo use. We are systemically identifying peptide epitopes on gp120 which are recognized by CTL from healthy, uninfected individuals, thus providing important information for vaccine design as well as for selective epitope targeting by immunologic effector cells. We will combine their expertise in enzymology and gene expression to characterize existing HIV POL over-expressors they have produced in the baculovirus system. Analysis of both forms of reverse trancriptase (RT), integrase, RNAase H and protease in this eukaryotic system will provide critical substrates for drug design and screening. The potential for delivering these compounds to HIV-infected cells via the CD4 structure will be investigated.